The overall goal of these experiments is to investigate the role(s) which exogenous GM1 gangliosides may play in ameliorating or preventing neural atrophy following peripheral auditory insults during maturation. specifically, mice and guinea pigs will be used to: 1) determine if ganglioside applications will negate changes in auditory brainstem responses following reversible neonatal conductive losses; 2) if ganglioside application will negate neuronal atrophy of superior olivary nuclei following a neonatal conductive loss; 3) to determine the effects of GM1 ganglioside and cochlear insults on the dendritic arborizations of cochlear nucleus neurons. These experiments will relate directly to the possible use of exogenous gangliosides in young patients with peripheral auditory disorders. Methods to be used include recording evoked auditory responses, animal surgery, and various light microscopic techniques.